Rotating disc scraper

ABSTRACT

This disclosure involves a scraper having freely rotating discshaped cutters with their axes of rotation in the plane of a flat, circular common holder; each cutter&#39;&#39;s axis of rotation being at an angle from radial lines extending from the center of the holder, about which the holder is rotationally driven. The disc-shaped cutters are of thin cross section so that the disc edges easily cut into tough or gummy surfaces as they are driven in circular patterns by the holder.

United States Patent Boyd 1451 July 25, 1972 [54] ROTATING DISC SCRAPER780,965 1 1905, Ohsner ..15/10413 2,150,806 3/1939 McDermet et a1...l5/104.l3 Inventor: Reed y n Wagner, Attor- 3,216,041 11/1965 Walters..15/236 ney at Law, 1041 E. Green St., Suite 202, Pasadena, Calif. 91101 Primary Examiner-Leon G. Machlin A! '-J h E. W 221 Filed: April 6,1970 [21 Appl. No.: 25,647 ABSTRACT This disclosure involves a scraperhaving freely rotating disc shaped cutters with their axes of rotationin the plane of a flat, [52] US. Cl IS/2326:; 92/5; circular Commonholder; each cunefs axis ofmtation being at lnt. Cl- B C an angle fromradial lines extending from the center of the Field of Search H 1 5/23693 10413 10414; holder, about which the holder is rotationally driven.The disc- 29/81 J, 1 3, 4, 114/222; 241/293; shaped cutters are of thincross section so that the disc edges 299/89, 90, 80; 90/17; 175/ 42easily cut into tough or gummy surfaces as they are driven in circularpatterns by the holder. 't d 1 References e 7 Claims, 12 Drawing FiguresUNITED STATES PATENTS R26,637 7/1969 Vaughn ..l5/93 R X I l I Y PATENTEHJUL25 I822 SHEET 1 0F 4 INVENTOR. Rim) L. BOYD PATENTEUJMSIQIZ 3,678,532

SHEET 2 OF 4 INVENTOR. Ree Bow PATENTEU JULZS I972 sum a nr 4 INVENTOR.REED L by B PATENTEDJULZSIHIZ 357 532 SHEU 4 0F 4 INVENTOR. Qaeb L. Eon:

ROTATING DISC SCRAPER BACKGROUND OF THE INVENTION Cutting or scraping oftough and gummy surfaces has been a continuing problem for both home andindustry. There are a large number of materials, including many paints,plastic resins and petroleum deposits which are too tough to cut with asimple blade cutter, and at the same time are too gummy to cut withabrasive means. One typical example of such a problem surface is apainted concrete floor. Removal of old paint is virtually impossiblewith a scraping blade, and even the coarser power sanding discs andbelts become almost instantly clogged with paint. Another examplerelates to automobile refinishing. Old wax and paint are extremelytough, and tend to fill the cutting surfaces of even relatively coarsefiles and sanding machines. As a result, extremely coarse cuttingsurfaces are used which abrade the underlying metal to the extent thatconsiderable time must be spent in filling and priming to cover up thedamaged surface. Still another example exists in the laminated resinbonded glass fiber material industry. Laminating resins areintentionally manufactured to retain a sticky surface after fullycuring, to insure the integrity of the bond to the next layer of thelaminate. Therefore, smoothing or trimming a resin bonded glass fibermaterial part is extremely troublesome. Power sanders become instantlyclogged, and even hand files become tightly clogged within a few minutesof use on the always sticky surfaces. There are many more similarproblems in various industries, where it is necessary to clean floorsand other surfaces of grease deposits, plastics, food residues, etc.,and where these substances are usually scraped by hand because of thelack of suitable power equipment to do the job faster and moreefficiently.

Previous attempts to solve this type of problem have resulted in thedevelopment of metallic sandpapers", as well as the development of bothhand and power-driven versions of relatively open-surfaced stamped sheetmetal files. Each of these solutions has resorted to a very roughcutting surface which tends to score and abrade the work surfaces.Further, although the new cutting surfaces cut soft materials readily,they tend to dull rather quickly on abrasive workpieces, such as resinbonded glass fiber material, or on an underlying substrate likeconcrete.

The object of this invention is to provide a tool for scraping andcutting tough and gummy materials which is completely non-clogging,which is well adapted to both manual and power operation, which hasself-renewing or self-sharpening cutting edges and which does not haveirregular, jagged cutting surfaces to undesirably abrade the worksurfaces or underlying substrates.

SUMMARY OF THE INVENTION The object of the invention is achieved by arotary scraper or cutter having a number of thin-walled, circularcutting discs in which the discs essentially stand on edge on the worksurface so the axes of the discs are generally parallel to the worksurface. The discs are free to rotate about their axes, and are held anddriven about a circular pattern by one or more rotating holders. Eachholder rotates about an axis generally normal to the work surface, andholds a number of cutting discs on several axes which are generally inthe common plane of the holder, and are at an angle with respect toradial lines passing through the axis of rotation of the holder. As theholder is driven about its axis, each of the cutting discs is free toroll in a generally circular pattern on the work surface.

The angle of each cutting disc axis with respect to the holders axis ofrotation causes each cutting disc to be at some angle across the tangentline of the circular path the cutting disc is inscribing on the worksurface, thereby creating a combined rolling and scraping action ofthe-edge of the cutting disc against the surface.

In a typical rotary scraper embodiment in its simplest form, threecutting discs are equally spaced about the periphery of a circularholder, so that all three cutting discs are in contact with even acompound-curved work surface. As the holder is rotated, the discs cut acircular pattern, and as the rotary scraper is translated along the worksurface, a cutting path is produced having a width equal to the diameterof the circular pattern. More complex embodiments include additionalcutting discs on each disc axis, additional disc axes within the holder,and multiple holders in a more complex rotary scraper.

Several means are usable to drive the holders in their rotary motion,such as, combustion engines or electric motors. The angle of theindividual cutters with respect to the tangent line of their circularpaths can be established to cause the rotary scraper to autorotateduring translation along the work surface. This negates the need forexternal power to drive the holders in rotation, since some of thetranslation work is converted into rotary motion, and makes the rotaryscraper particularly well adapted to small, manually operated devices.

Although the cross sectional configurations of the cutting discs arevaried for optimum cutting efficiency depending on the workpiecematerial properties, operating experience with this type of cutter hasshown that each disc must be quite thin with respect to its diameter tocut effectively under reasonably low cutting pressures, and to maintaina sharp cutting edge as the diameter of the cutter is reduced by wear.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of theunderside of a rotary scraper illustrated as a cutting and scrapingattachment to a floor treating machine.

FIG. 2 is a perspective view of the upper side of the machine in FIG. I,having portions of the machine housing and the rotary scraper cut awayfor clarity.

FIG. 3 is a cross sectional view of the: rotary scraper showing thestructure of the cutting discs and holder.

FIG. 4 is a partial top elevation view of the scraper showing a means ofattachment and adjustment of the cutting discs.

FIG. 5 is a diagram of the cutting geometry of the cutting discs in apower driven machine.

FIG. 6 is a perspective view of the underside of a rotary scraper havinginterlocked cutter angle adjustment.

FIG. 7 is a perspective view of the invention as adapted for use in apower sanding machine.

FIG. 8 is a perspective view of the invention as adapter for use in aportable electric drill.

FIG. 9 is a perspective view of the invention as adapter for use in ahome-type floor polishing machine.

FIG. 10 is a diagram of the cutting geometry of the cutting discs in anon-powered autorotation operation.

FIG. 11 is a perspective view of the invention as adapted for use as ahand scraper.

FIG. 12 is a perspective view of the invention as adapted for use in aplane-surface hand scraper.

Now refer to FIG. 1 in which the scraper 10 may be seen mounted on theshaft 11 of a commercial floor treating machine 12 including a housing13, motor 14, transporting wheels 15, and handle 19. A number of cuttingdiscs 16 are shown rotatably supported on three shafts 17 which areequally spaced about a generally circular holder I8. The wheels 15 clearthe floor in operation, and may be engaged to transport the machine bymoving the handle 16 downwards. Energizing motor 14 causes shaft II torotate, thereby moving discs 16 about the axis of rotation of holder 18.

Now refer to FIG. 2 wherein the scraper 10 may be seen mounted on motorshaft 11 within the partially cut away machine housing 13. Cutting discs16 are shown supported on shafts 17, which are attached to the partiallycut away holder 18 through bearing blocks 20a&b, and fasteners 21 and22.

Now refer to FIG. 3 in which the cross sectional view of the rotaryscraper 10 is shown with discs 16 located on shaft 17 by spacers 23.Shaft 17 is in turn supported by bearings 24 retained by nut 25. Thebearing block 20 is attached to holder 18 by fasteners 21 and 22. Holder18 is provided with a hub 26 suitable for motor shaft attachment. Inthis view, the discs 16 are shown to have a preferred shape as a portionof a sphere. This is a relatively low-cost configuration presenting acutting edge having a rake angle, and having high stiffness even with avery thin wall as would be possible in a hard material, preferablysteel. The use of the illustrated shape for steel cutters has provenmost effective in models tested in applications such as the removal ofold paint and grease deposits from concrete floors. In theseapplications, it has been found that the thin steel edges, approximately0.032 inches thick for a 4 inch diameter cutter, in an arrangementalmost precisely as illustrated in FIG. 3, were very effective incutting off paint and grease with no perceptible damage to the floor.

Now refer to FIG. 4 which is a partial top elevation view of the scraperas indicated by the viewing plane AA in FIG. 3, and showing bearingblock 20 pivotally attached by fastener 22, with the cutter angleadjustably retained by fastener 21; fastener 21 being threaded intoblock 20 and having side clearance for adjustment in slot 27 of holder18. Experience with prototype models has shown an adjustment rangebetween and for angle A to be adequate to cut a wide variety of surfacematerials, there being an optimum cutter thickness and shape, diameter,working circle, cutting speed and cutter angle A for each material to becut. Two additional configurations for the cutting discs are shown as aflat disc 30 and a serpentine-edged disc 3!. The use of the flat disc 30is indicated where cost of the unit is a critical factor, since flatsteel discs are some of the lowest possible cost cutters. Theserpentine-edged cutting disc 31, as in the case of the previouslydescribed spherical form, is a means of providing increased cutterstiffness and still maintaining a thin cutting edge. There are somescraping applications where this is very desirable, particularly wherethe disc material must be somewhat soft. One such case is in thecleaning of deposits such as bakery dough or food residue fromvinyl-surfaced floors. It is imperative that the cutter be of a materialharder than the residue being scrapped off, but still softer than thevinyl and perhaps even the wax finish on the floor, and this becomespossible by using materials such as polyethylene plastics for the discs.

Now refer to FIG. 5 wherein a diagram of the cutting geometry of thescraper, which is a simplification of a typical unit such as the floortreating machine shown in FIG. 1. The diagram shows cutting discs 16equally spaced on a radius R and rotated in direction D. Angle A is theangle of the cutter axis with respect to a radial line from the centerof rotation of shaft 11. If angle A were zero and the cutting discs havetrue point contact with the work surface, which is only theoreticallypossible, the cutting discs 16 would merely roll freely about radius Rwithout cutting. The actual existence of line contact as opposed topoint contact means that some translational movement, and hence somecutting, will occur. Increasing angle A increases the magnitude of thetranslational movement or scraping action of the cutting disc, cuttinggrooves 32 and producing chips 33.

Now refer to FIG. 6 showing a perspective view of the underside ofanother embodiment of the scraper including a means for simultaneouslychanging the cutting angle of all of the discs 16. A toggle link 41 ispivotally attached to the inner end of block 20, and the other end ofeach toggle link 41 is pivotally attached to a rotatable ring 42 aroundhub extension 43, whereby rotation of the ring 42 will simultaneouslymove all of the blocks 20 through a change of cutting angle. A lockingfastener 44 is positioned in an arcuate slot 45 to lock the adjustmentduring operation. A form of fluid-moving blade 46 is shown attached tothe underside of holder 18, so formed as to sweep cut material fromunder the machine during rotation of the scraper.

Now refer to FIG. 7 wherein a scraper 50 is particularly adapted for useon a commercial power sanding disc machine 51. A plurality of smalldiameter cutting discs 52 are positioned to partially extend from thesurface of holder 53 in a manner convenient for use in operations suchas removing paint from an automobile body.

Now refer to FIG. 8 wherein a scraper 60 is particularly adapted for usein a portable electric drill 61. A plurality of small diameter cuttingdiscs 62 are positioned to partially extend from the surface of holder63 to engage a work surface. A shaft 64 is provided on holder 63 toadapt the scraper for rotating and support by a drill chuck 65.

Now refer to FIG. 9 wherein two scrapers 70a and 70b are adapted for usin a typical home floor polishing machine 71. A plurality of smalldiameter cutting discs 72g and 72b are positioned to partially extendfrom the respective surfaces of holders 73a and 73b in a mannerconvenient for use in operations such as removing paint from a floor.

Now refer to FIG. 10 wherein a diagram of the cutting geometry is shownfor a scraper that is not powered in rotation, but instead autorotatesduring translational movement along the work surface. In this diagram,three cutting discs 16a, 16b and 16c are equally spaced about theperiphery of a holder on radius R, each disc being set at a cuttingangle A with respect to the radial line extending from the center ofrotation of shaft 11. The scraper is moved in translation in directionE. Disc 16 a when moved in direction E will attempt to roll in thedirection normal to its axis of rotation, and thereby produces a forceFa, producing additional torque in direction G. Similarly, disc 16b whenmoved in direction E will also attempt to roll in a direction normal toits axis of rotation, and thereby produces a force Fb, producingadditional torque in direction G. Disc 160 when moved in direction Ewill simply attempt to roll normal to its axis of rotation, which is inthe direction E and imparts no instantaneous torque. Any accumulativetorques applied by the discs in all locations are all in the samedirection to produce autorotation from translational movement.

Now refer to FIG. 11 wherein a scraper is particularly adapted for usein a handle 81. A plurality of small diameter cutting discs 82 arepositioned to partially extend from the surface of a holder 83 which isfree to rotate on shaft 84, so that motion in direction M causesautorotation of the discs and holders.

Now refer to FIG. 12 wherein a scraper is shown having a planar body 91.A plurality of small diameter cutting discs 92a, 92b and 92c arepositioned to partially extend from the respective surfaces of each ofthree holders 93a, 93b and 93c which are free to rotate on respectiveshafts 94a, 94b and 94c, so that motion in direction N imparted throughhandle 95 causes autorotation of the discs and holders.

The foregoing descriptions have included components and geometries tomost clearly illustrate the concept of the invention. Operatingexperience has shown that each combination of surface material to beremoved, hardness of the underlying substrate and speed and weight ofthe driving machine calls for a specific cutting disc shape, thickness,distribution and angle in the holder or holders, as well as a preferredcutter spacing to preclude clogging.

In some applications where more severe scraping action is desired, it isdesirable to lock the rotation of the individual cutting discs so asingle cutting edge on each disc is presented to the work surface, butthe discs may be unlocked and manually turned when a new cutting surfaceis desired by the operator.

The above described embodiments of this invention are merely descriptiveof its principles and are not to be considered limiting. The scope ofthis invention instead shall be determined from the scope of thefollowing-claims including their equivalents.

I claim:

1. A rotary cutter comprising a frame including central connecting meansfor securing said frame to a drive shaft of a mo- 101',

a plurality of axles secured to said frame and extending generallyradially from said central connecting means,

at least one cutter journaled on to each axle for rotation by engagementwith a surface to be cut, said cutters comprising thin discs withcontinuous edges in contact with the surface to be cut defining a planarcutting surface and said discs constituting the support for said rotarycutter and driving motor, and means for changing the angle of axles withrespect to lines passing through the axis of rotation of the frame.

2. A rotary cutter in accordance with claim 1 wherein said anglechanging means is capable of changing the angle of the axles between 0and 3. The combination in accordance with claim 1 wherein said cutterscomprise cupped discs.

4. The combination in accordance with claim 1 including common meansconnected to each of said axles whereby said axles may be simultaneouslyadjusted in angle with respect to the radius.

5. A rotary cutter comprising a frame including central connecting meansfor securing a frame to a drive shaft of a motor, a plurality of axlessecuring to the frame and extending generally radially from the centralattachment means, at least one disc journaled on to each axle forrotation by engagement with a surface to be cut, said cutters comprisingdiscs with continuous edges in contact with the surface to be cut, andcommon means connected to each of said axles for changing the angle ofaxles with respect to lines passing through the axis of rotation of theframe, said common means comprise a ring secured to the frame andindividual toggles coupled to respective axles whereby rotary movementof the ring about the axis of rotation of the frame produces a similarchange in angle to the axles.

6. The combination in accordance with claim 5 wherein each axle ismounted on a pivoted bearing block and each toggle engages an innerportion of the respective bearing block.

7. The combination in accordance with claim I wherein said frame iscircular and includes a plurality of blade members extending downwardinto the regions between said cutters for ejecting cut debris from underthe frame on rotation of said frame.

1. A rotary cutter comprising a frame including central connecting meansfor securing said frame to a drive shaft of a motor, a plurality ofaxles secured to said frame and extending generally radially from saidcentral connecting means, at least one cutter journaled on to each axlefor rotation by engagement with a surface to be cut, said cutterscomprising thin discs with continuous edges in contact with the surfaceto be cut defining a planar cutting surface and said discs constitutingthe support for said rotary cutter and driving motor, and means forchanging the angle of axles with respect to lines passing through theaxis of rotation of the frame.
 2. A rotary cutter in accordance withclaim 1 wherein said angle changing means is capable of changing theangle of the axles between 0* and 15* .
 3. The combination in accordancewith claim 1 wherein said cutters comprise cupped discs.
 4. Thecombination in accordance with claim 1 including common means connectedto each of said axles whereby said axles may be simultaneously adjustedin angle with respect to the radius.
 5. A rotary cutter comprising aframe including central connecting means for securing a frame to a driveshaft of a motor, a plurality of axles securing to the frame andextending generally radially from the central attachment means, at leastone disc journaled on to each axle for rotation by engagement with asurface to be cut, said cutters comprising discs with continuous edgesin contact with the surface to be cut, and common means connected toeach of said axles for changing the angle of axles with respect to linespassing through the axis of rotation of the frame, said common meanscomprise a ring secured to the frame and individual toggles coupled torespective axles whereby rotary movement of the ring about the axis ofrotation of the frame produces a similar change in angle to the axles.6. The combination in accordance with claim 5 wherein each axle ismounted on a pivoted bearing block and each toggle engages an innerportion of the respective bearing block.
 7. The combination inaccordance with claim 1 wherein said frame is circular and includes aplurality of blade members extending downward into the regions betweensaid cutters for ejecting cut debris from under the frame on rotation ofsaid frame.